This invention relates in general to certain new and useful improvements in reinforced plastic tubular products and the method and apparatus for producing the same, and, more particularly, to reinforced plastic tubular products which are tapered along their axial length, and the apparatus and method for producing such tapered reinforced plastic tubular products.
In recent years, the use, and acceptance of tubes and pipes formed from reinforced plastic materials has received increased prominence. Until recently, only metal tubes were used in various applications, since it was believed that only structural metals were capable of withstanding torsional and bending strengths to which the tubular members were subjected. The advent of reinforced plastic tubular members provided a significant advance in the solution of the problems which were previously solved by the use of tubular metal members.
In view of the increased recognition of the use of reinforced plastic members, there has been much research and development activity in the production of such reinforced plastic members. Generally, such reinforced plastic tubular members have been produced on a continuous mandrel which extends and moves in a horizontal plane past a series of winding wheels capable of winding convoluted patterns of reinforcement material on the continuously moving mandrel. For example, one typical example of such winding mechanism is more fully illustrated and described in U.S. Pat. No. 3,769,127, to Goldsworthy, et al. However, the commercially available conventional apparatus are not capable of winding on reinforcing strand material on tubular mandrels of a tapered shape.
Generally, the filament winding apparatus which have been described in the prior art, as exemplified by the aforementioned U.S. patent, essentially are only capable of winding on mandrels of a constantly sized diameter, and are not capable of effectively winding on mandrels of non-constant cross-sectional shape. One of the typical problems encountered is in winding upon and applying the filament reinforcement to a mandrel of non-constant cross sectional size and shape is that strands which are applied on a subsequent basis tend to be applied at different angles and at different speeds, relative to the movement of the mandrel through the filament winding apparatus. This was deemed to create considerable problems in applying the strands at a constant tension and in the desired pattern.